diff --git a/Library/Homebrew/abstract_command.rb b/Library/Homebrew/abstract_command.rb
index cd4f299749294..9927c0fa8780c 100644
--- a/Library/Homebrew/abstract_command.rb
+++ b/Library/Homebrew/abstract_command.rb
@@ -9,7 +9,7 @@ module Homebrew
   # - Each Command lives in an isolated namespace.
   # - Each Command implements a defined interface.
   # - `args` is available as an ivar, and thus does not need to be passed as an argument to helper methods.
-  # - Subclasses no longer need to reference CLI::Parser directly.
+  # - Subclasses no longer need to reference `CLI::Parser` or parse args explicitly.
   #
   # To subclass, implement a `run` method and provide a `cmd_args` block to document the command and its allowed args.
   # To generate method signatures for command args, run `brew typecheck --update`.
diff --git a/Library/Homebrew/cmd/leaves.rb b/Library/Homebrew/cmd/leaves.rb
index e6fe1abd58597..ecd4e3d7df533 100644
--- a/Library/Homebrew/cmd/leaves.rb
+++ b/Library/Homebrew/cmd/leaves.rb
@@ -1,51 +1,49 @@
 # typed: true
 # frozen_string_literal: true
 
+require "abstract_command"
 require "formula"
 require "cask_dependent"
-require "cli/parser"
 
 module Homebrew
-  module_function
-
-  sig { returns(CLI::Parser) }
-  def leaves_args
-    Homebrew::CLI::Parser.new do
-      description <<~EOS
-        List installed formulae that are not dependencies of another installed formula or cask.
-      EOS
-      switch "-r", "--installed-on-request",
-             description: "Only list leaves that were manually installed."
-      switch "-p", "--installed-as-dependency",
-             description: "Only list leaves that were installed as dependencies."
-
-      conflicts "--installed-on-request", "--installed-as-dependency"
-
-      named_args :none
+  module Cmd
+    class Leaves < AbstractCommand
+      cmd_args do
+        description <<~EOS
+          List installed formulae that are not dependencies of another installed formula or cask.
+        EOS
+        switch "-r", "--installed-on-request",
+               description: "Only list leaves that were manually installed."
+        switch "-p", "--installed-as-dependency",
+               description: "Only list leaves that were installed as dependencies."
+
+        conflicts "--installed-on-request", "--installed-as-dependency"
+
+        named_args :none
+      end
+
+      sig { override.void }
+      def run
+        leaves_list = Formula.installed - Formula.installed.flat_map(&:runtime_formula_dependencies)
+        casks_runtime_dependencies = Cask::Caskroom.casks.flat_map do |cask|
+          CaskDependent.new(cask).runtime_dependencies.map(&:to_formula)
+        end
+        leaves_list -= casks_runtime_dependencies
+        leaves_list.select!(&method(:installed_on_request?)) if args.installed_on_request?
+        leaves_list.select!(&method(:installed_as_dependency?)) if args.installed_as_dependency?
+
+        leaves_list.map(&:full_name)
+                   .sort
+                   .each(&method(:puts))
+      end
+
+      def installed_on_request?(formula)
+        Tab.for_keg(formula.any_installed_keg).installed_on_request
+      end
+
+      def installed_as_dependency?(formula)
+        Tab.for_keg(formula.any_installed_keg).installed_as_dependency
+      end
     end
   end
-
-  def installed_on_request?(formula)
-    Tab.for_keg(formula.any_installed_keg).installed_on_request
-  end
-
-  def installed_as_dependency?(formula)
-    Tab.for_keg(formula.any_installed_keg).installed_as_dependency
-  end
-
-  def leaves
-    args = leaves_args.parse
-
-    leaves_list = Formula.installed - Formula.installed.flat_map(&:runtime_formula_dependencies)
-    casks_runtime_dependencies = Cask::Caskroom.casks.flat_map do |cask|
-      CaskDependent.new(cask).runtime_dependencies.map(&:to_formula)
-    end
-    leaves_list -= casks_runtime_dependencies
-    leaves_list.select!(&method(:installed_on_request?)) if args.installed_on_request?
-    leaves_list.select!(&method(:installed_as_dependency?)) if args.installed_as_dependency?
-
-    leaves_list.map(&:full_name)
-               .sort
-               .each(&method(:puts))
-  end
 end
diff --git a/Library/Homebrew/test/cmd/leaves_spec.rb b/Library/Homebrew/test/cmd/leaves_spec.rb
index 2b6fc51bee188..9e00a21ca1a4d 100644
--- a/Library/Homebrew/test/cmd/leaves_spec.rb
+++ b/Library/Homebrew/test/cmd/leaves_spec.rb
@@ -1,8 +1,9 @@
 # frozen_string_literal: true
 
+require "cmd/leaves"
 require "cmd/shared_examples/args_parse"
 
-RSpec.describe "brew leaves" do
+RSpec.describe Homebrew::Cmd::Leaves do
   it_behaves_like "parseable arguments"
 
   context "when there are no installed Formulae", :integration_test do